Strong scrummaging Arhip becomes the first signing of the John Mulvihill era and will compete with Wales internationals Dillon Lewis and Scott Andrews for the number three shirt.
During his five seasons at the Ospreys the 29-year-old built a reputation as a strong scrummager and a dynamic ball carrier around the field.
“I’m really excited to be joining Cardiff Blues at a really positive time for the region and I’m looking forward to the challenge that lies ahead,” said Arhip.
“I have been very impressed with the progress made at the Arms Park in the last couple of seasons, culminating in winning the Challenge Cup.
“It is a really exciting squad with so much young talent coming through and I am looking forward to adding my experience and competing with the other props. The conversations I’ve had with John Mulvihill have been really good and I’m excited about the vision he has set out.
“I also have a good relationship with new forwards coach Tom Smith, who also joins from the Ospreys.”
The signing of Arhip will please Mulvihill who is in the process of building a squad which can build on last seasons European Challenge Cup triumph.
“We are all thrilled to have signed Dmitri,” said the Australian.
“He has proven himself a world-class tighthead prop both in terms of scrummaging and around the pitch and is the perfect fit for us as we look to strengthen our pack.
“We need to add quality and depth to our squad to compete in both the Guinness PRO14 and the Champions Cup and this is a great start to our recruitment. We remain committed to developing Welsh talent from within, but you also need to strike the right balance.
“Dmitri will not only bring a wealth of experience for the entire season but he will have a responsibility to pass on his knowledge to the likes of Dillon and Kieron Assiratti, who have an abundance of potential.
“I am confident we now have real strength in depth and competition in a vitally important position.”